I am curious does Sofia frequently accompanies them in their outings? Maybe they are deliberately trying to mend the perception of bad blood between Letizia and Sofia by including her.
The purpose of the Mallorca trips is for the SRF to provide convenient photo ops to promote the narrative of happy family in a seemingly relaxed and normal setting and to be seen moving amongst normal people. Also you get the image of the king doing something sporty. Before the Cristina scandal, her family was also there. Before her divorce, Elena's family was also there. Felipe's family is all that's left that is perceived to be intact and "normal". It helps, too, that they're a photogenic family. Sofia will do anything to promote that narrative. Her son's monarchy requires it.
It's unfortunate the family is all broken up. It was nice seeing the whole group go out for a dinner at local restaurants and hanging out on a boat together. But things were probably never as they seemed. There was tension between Cristina/Inaki andLeti and the likely tension between Elena and her now ex-husband. It was never a truly happy family.
The family's real vacation happens after Mallorca when L&F and their daughters (no Sofia) go away for a few weeks on a truly private holiday.